1. Field Of The Invention
The present invention relates to improvements to solder extractors and to the tips utilized therein.
2. Description Of The Prior Art
The repair of electronic equipment often involves the need to remove solder fillets and joints efficiently without otherwise affecting the circuit as a whole or the components therein. Generally speaking, solder extraction is performed by applying the front end of a heated tubular element to a soldered area to melt the solder. Suction is then applied to the rear end of the tubular element to draw the molten solder off into the tube.
Siegel, U.S. Pat. No. 3,392,897, discloses a solder extractor comprising a coaxial instrument of pencil-type construction in which a tubular heated tip, a heat generating element, a molten solder receiving chamber and a gripping handle are all disposed in concentric and/or axial succession with respect to one another, with an axial passageway front to rear for the flow of extracted solder. The tubular heated tip is replaceable since the tip will become worn, due to the corrosive action of the solder, and/or will become burdened with solder after prolonged usage. To facilitate ready replacement of the tip, the tip is generally formed as a tubular member which is receivable within the axial passage through the heating element and held in place by a transverse set screw bearing on one side of the tip. Moreover, to maintain a low fabrication cost, the tips are not closely toleranced with respect to the axial passage but are merely made small enough to readily fit into the axial passage, bearing in mind that there will be variations in the dimensions of the axial passage between different extractors.
However, while these measures maintain the tip as a low cost item, they also create problems with the operation of the extractor. In particular, the utilization of a set screw to hold the tip in place may result in the tip being forced to one side of the axial passage through the heating element. This displacement has two detrimental effects, it impairs heat transfer to the tip because of limited contact with the inner surface of the axial passage through the heating element (e.g., in the worst case, the tip may only make a line contact with the heating element) and the gap between the tip and the heating element allows loss of vacuum pressure (for drawing molten solder through the tip).
Vella, U.S. Pat. No. 4,328,290, also discloses a solder extractor which may utilize a set screw to hold the hollow tip in place. More particularly, the Vella patent discloses a control system for temperature control of the tip wherein the temperature of the heating element is monitored and the power supply to the heating element is controlled in response to the measured temperature of the heating element in order to maintain a predetermined temperature. However, such a control system presupposes adequate thermal contact between the tip and the heating element and, as previously noted, a set screw mount for the tip in the heating element does not insure consistent or adequate thermal contact.